A spark plug has been known in which an electrode includes an intermediate member interposed between an electrode base member and a tip formed of an alloy containing Pt as a main material, in order to inhibit flame quenching in which the electrode deprives the energy of a flame kernel. In a spark plug disclosed in International Publication No. 2010/029944, a first electrode opposing a second electrode with a spark gap includes: an electrode base member containing Ni as a main material; an intermediate member that is formed of an alloy containing Ni as a main material and is welded to the electrode base member so as to protrude from the electrode base member; and a melt portion formed by melting the intermediate member and a tip formed of Pt—Rh together. A first electrode of a spark plug disclosed in International Publication No. 2009/063930 includes: an electrode base member containing Ni as a main material; an intermediate member containing Ni as a main material; and a melt portion formed by melting the intermediate member and a tip formed of Pt—Ni together.
However, in the technique disclosed in International Publication No. 2010/029944, partial wear (hereinafter also referred to as “hollow”) of the melt portion may occur when the spark plug is used at a high temperature. In the technique disclosed in International Publication No. 2009/063930, wear of the intermediate member may occur when the spark plug is used at a high temperature or in an engine with a supercharger.
The present invention is made in order to address the aforementioned problems. An advantage of the present invention is a spark plug capable of improving wear resistances of the intermediate member and the melt portion.